Overexpression of microRNA-133b is associated with the increased survival of patients with hepatocellular carcinoma after curative hepatectomy: Involvement of the EGFR/PI3K/Akt/mTOR signaling pathway

The aim of the present study was carried out to investigate the association of microRNA-133b (miRNA-133b) expression with the prognosis of patients with hepatocellular carcinoma (HCC) after curative hepatectomy. In the present study, the expression of miRNA-133b in HCC tissues was determined to be lower than that noted in the adjacent normal tissues. Overall and disease free survival of the HCC patients with high miRNA-133b expression was observably extended, compared with the HCC patients with low miRNA-133b expression. Moreover, the overexpression of miRNA-133b inhibited cell proliferation, increased lactate dehydrogenase (LDH) activity, induced apoptosis and promoted caspase-3/-8 activities and Bax/Bcl-2 protein expression in HCC cells, whereas the protein expression of epidermal growth factor receptor (EGFR) was significantly decreased. The overexpression of miRNA-133b significantly suppressed PI3K, phosphorylated (p)-Akt and p-mTOR protein expression in HCC cells. GW2974, an EGFR inhibitor, suppressed the protein expression of EGFR, inhibited cell proliferation, increased LDH activity, induced apoptosis and promoted caspase-3/-8 activities and Bax/Bcl-2 protein expression, downregulated PI3K, p-Akt and p-mTOR protein expression in the transfected HCC cells overexpressing miRNA-133b. Taken together, our results indicate that the overexpression of miRNA-133b is associated with the increased survival of HCC patients after curative hepatectomy. The effects of miRNA-133b in HCC are mediated through the EGFR/PI3K/Akt/mTOR signaling pathway.